<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body{
           background: aqua;
        }
        .m{
            width: 15%;
            margin: 20px auto;

        }
        .as{
            height: 250px;
        }
        .common {
            width:230px;
            height: 30px;
        }
    </style>
</head>
<body >
<div class="as">
    <div class="m">
        <form action="myservelt" method="get">
            姓名: <input type="text"class="common"name="username">
            密码: <input type="password"class="common"name="password">
            <select class="common"name="select">
                <option selected="selected"value="仙型水稻">仙型水稻</option>
                <option value="碱性水稻">碱性水稻</option>
                <option value="种子">种子</option>
            </select>
            <input type="checkbox"name="check" value="man">男
            <input type="checkbox"name="check" value="female">女

            <input type="submit"class="common">
        </form>
    </div>
</div>
</body>
</html>